"AP physics"

Specimens To Supplement the Most Widely-Used College Lab Manual for Physical Geology

Gray and poorly sorted, with a gritty texture.

Everything Students Need to Work Independently to Identify Rocks and Minerals

Lustrous, black 'hard coal'.

Coarse-grained, with microcline, biotite and horblende phenocrysts.

Glassy; most specimens float in water.

Shiny black volcanic glass showing conchoidal fracture and some spherulites.